The disease is very rare in the U.S. because most people are vaccinated against it. The CDC recommends that all children be vaccinated against diphtheria with a vaccine that also protects against tetanus and whooping cough (pertussis). Because immunity can fade over time, the CDC also recommends that teens and adults get a booster shot every 10 years.

Why do I need this test?

You may need this test to find out whether you have or are at risk for diphtheria if your diphtheria antibodies resulting from the vaccine are too low or have faded since your last vaccine.

Although the disease is rarely seen in the U.S. and other developed countries, you may be at risk if:

You are an adult and haven't had a diphtheria booster shot

You recently traveled to a country where diphtheria is common

You recently moved to the U.S. from a country where diphtheria is widespread

What other tests might I have along with this test?

Your healthcare provider may also order a culture test for the diphtheria bacteria. A positive culture test tells your provider that you have diphtheria.

What do my test results mean?

Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

Results are given in international units per milliliter (IU/mL). If you have been vaccinated against diphtheria, your minimum levels of antibodies should be at least 0.01 to 0.1 IU/mL.

If your test results show a level lower than that, you may be at risk for diphtheria. If you have certain symptoms, you may need additional tests to find out whether you actually have diphtheria.

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand.

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore.

What might affect my test results?

Other factors aren't likely to affect your results.

How do I get ready for this test?

You don't need to prepare for this test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.

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